In an interim readout from the Phase 2 STARBORN-1 trial in pediatric lymphatic malformations, 100% of the eight patients who reached the eight-week response assessment met the study’s definition of clinical success. Among 10 patients who completed treatment, 80% achieved clinical success. In the macrocystic subgroup, 83% (5/6) registered complete responses, with one additional substantial response. No serious adverse events were reported; the most common events were swelling and fatigue, with one discontinuation for Grade 2 fatigue.
The update covers 12 children treated with intracystic TARA-002, an inactivated streptococcal preparation derived from the same master cell bank as OK-432, a standard of care in Japan. Patients receive up to four injections approximately six weeks apart. Seven of eight evaluable patients achieved clinical success with one or two doses; one patient with a 1,739 ml macrocystic lesion required all four injections and achieved a complete response. Two participants have reached 32 weeks post-treatment and remain disease-free. Two patients withdrew before the eight-week assessment—one later found to have a rare cancer and one who left after marked improvement. One patient initially categorized as a complete responder was subsequently reclassified as having a ranula, highlighting diagnostic nuance in maxillofacial cysts. The study is planned to enroll 29 patients with macrocystic or mixed cystic disease, using volumetric reduction on imaging or investigator assessment to define outcomes.
Strategically, Protara is executing a fast-follower adaptation of a long-utilized therapy in Asia to the U.S. regulatory framework, seeking to convert decades of real-world use of OK-432 into a modern, U.S.-manufactured, pediatric rare disease program. The single-arm, open-label design, combined with notable response rates and a benign safety profile, suggests the company is testing whether robust effect size and durability can support a streamlined pathway, potentially aided by Rare Pediatric Disease designation and the prospect of a priority review voucher. The central tension is evidentiary: FDA will scrutinize measurement rigor, lesion classification, age de-escalation safety, and durability across mixed cystic presentations, as well as CMC comparability for a biologic with procedural administration.
For sites, the model fits existing workflows in tertiary pediatric centers where interventional radiology and ENT teams routinely manage LMs with off-label sclerosing agents or surgery. If outcomes hold, demand could shift toward standardized intracystic regimens with clearer dosing guidance and manufacturing controls, reducing reliance on ad hoc sclerosant selections. Imaging core lab capabilities and consistent volumetric assessment will be pivotal; the mixed use of axial imaging and investigator assessment introduces variability that sponsors and CROs will need to tame with protocolized reads and training. Regulators will weigh whether single-arm data with external benchmarks suffice in a setting without approved therapies, or whether a comparative study against common sclerotherapy agents will be required. Payers will eventually focus on procedure frequency, anesthesia exposure, and retreatment rates versus surgery and current off-label options.
What’s next is validation at scale and over time: full enrollment to 29 patients, maturing follow-up beyond 32 weeks, and clarity on the registrational strategy. A clean safety profile in the youngest age cohorts will be decisive. Manufacturing and lot-to-lot consistency for a cell-derived product administered locally could become a gating factor as the program moves from limited-site execution to broader availability. Watch for central imaging adoption, endpoint tightening, and any FDA feedback on acceptable control strategies. Also notable is portfolio prioritization, as Protara advances TARA-002 concurrently in NMIBC; capital allocation between oncology and pediatric rare disease will shape timelines. If the response signal persists with durable control and standardized assessments, the path to a U.S. filing could be shorter than typical for procedural biologics—provided the evidentiary and CMC risks are managed early.
Jon Napitupulu is Director of Media Relations at The Clinical Trial Vanguard. Jon, a computer data scientist, focuses on the latest clinical trial industry news and trends.
